Phosphatides occur widely in vegetable and animal matter, but soybeans are the principal commercial source. In the refining of crude vegetable oils, it is conventional to remove phosphatides (frequently referred to as lecithin) from the oil. This process is commonly referred to as "degumming". Degumming is typically achieved by hydrating the lecithin-containing crude oil and recovering the insoluble hydrated lecithin (frequently referred to as "wet gum") from the oil. A commercial lecithin product is then obtained by drying the wet gum. The lecithin of commerce ordinarily contains about one-third oil and about two-thirds phosphatides. Such commercial lecithin products generally have an acetone insoluble (A.I.) of at least 50 and are most typically within about the 60 to about 65 A.I. range. In the trade, 65% A.I. commercial lecithin is a familiar commodity.
The difficulties encountered with commercial vegetable lecithin are due to its viscosity characteristics and a tendency to settle and form layers upon storage. Such lecithins are fairly viscous when first prepared, but subsequently solidify or develop a heavy layer which separates from a lighter oily layer. This tendency to solidify or settle into a hard lower layer and an oily top layer is accentuated under cold storage conditions.
Considerable inconvenience, loss and waste of lecithin also arises through the commercial use of high viscosity lecithins. The high viscosity lecithins tend to stick to equipment and containers which make it difficult to accurately weight, transfer and expeditiously use the lecithin product in recipes formulated therewith.
The art has sought to overcome the aforementioned shortcomings by numerous different approaches. It has been recognized that the low viscosity 65 A.I. lecithins are less prone to separate and form a plastic mass and can be more easily handled. A common practice is to introduce fluidization agents to control the fluidity or viscosity of the lecithin. One approach is to use a diluent such as an oil or solvent adjunct to fluidize the lecithin mixture. Such an approach has the disadvantage of reducing the A.I. value while introducing non-functional and undesirable diluents into the lecithin product. Numerous other patents suggest that lecithin may be fluidized with a wide variety of acids (e.g. U.S. Pat. Nos. 2,194,842--fatty acids; 2,374,681--sulfonic acid; 2,391,462--aqueous acid; 2,483,748--fatty acid esters; 2,494,771--aliphatic acid; 2,555,137--lactic acid, etc.) in varying amounts. U.S. Pat. No. 2,686,190 reports that lecithin can be converted to a more fluid form without requiring the presence of fluidization agents by reducing the water content of the wet gum to not more than about 0.3% by weight water. Another U.S. Pat. No. (3,357,918) indicates that certain salts of magnesium, calcium and aluminum impart fluidity to lecithin in specified amounts.
Numerous other patents (e.g. see U.S. Pat. Nos. 3,878,232; 4,162,260; 2,351,184; 2,576,958 and 2,666,074, French Pat. Nos. 1,388,671 and 1,385,670 and British Pat. No. 1,053,807) physically separate or fractionate certain components from lecithin-containing oils to provide a refined oil product which, in some instances, reportedly improves upon the quality of lecithin.
Enzymatic treatments which alter phospholipid structure have been reported. U.S. Pat. No. 4,119,564 reports the treatment of phospholipoproteins with phospholipase A (snake venom) to increase the viscosity imparting properties of the lecithin in oil-in-water emulsions. Similarly U.S. Pat. No. 4,141,792 reports the quantitative analysis of phospholipids content by enzymatically treating test samples with certain phospholipases. Lecithin has also been treated with enzymes which split off the fatty acid radicals (e.g. esterases--Kirk-Othmer Encyclopedia of Chemical Technology, 2nd Ed., Volume 12, page 349).
As evident from the above, two saliently different approaches have been taken to improve 65 A.I. lecithin products. One approach involves physical purification to remove certain impurities from the lecithin-containing oil-base stock while the other approach relies upon the addition of fluidization agents. The first approach typically involves substantial capital expenditures, costly and tedious processing controls, etc., for improvements, which in many instances, do not significantly improve or correct the aforementioned lecithin deficiencies. Similarly the addition of fluidization agents does not afford a satisfactory solution. Lecithin products are known to vary considerably from one manufacturing lot to another. The character and nature of soybean raw materials (which vary considerably due to variety, climate, maturity, etc.), the processing and manufacturing conditions and other related matters make it difficult to accurately control or regulate the precise amount of fluidization agents needed to achieve the desired affect in any given manufacturing lot. Moreover, such additives often destroy or mask other desirable functional or physical attributes of the native lecithin product. Due to a wide variety of industrial, pharmaceutical, agricultural and food applications, such additives often become incompatible with the recipe components and its intended end-use.
Notwithstanding a long-felt need to improve upon these deficiencies, the prior art has made relatively minor progress in improving upon lecithin manufacture. A simplified, cost-effective 65 A.I. lecithin manufacturing process which would not contaminate or destroy the indigenous characteristics of lecithin would be of substantial benefit. The inventors discovered that the problems, which have heretofore plagued the prior art, can be effectively overcome by hydrolyzing the polysaccharide component of lecithin-containing oil-based stocks or other lecithin-containing compositions with carbohydrases. Through the conversion of these polysaccharides into hydrolyzates, fluid lecithins which remain stable over prolonged storage periods under diverse climatic conditions without requiring supplemental additives are now feasible.